1. Field
The present disclosure relates generally to quantum communication and, in particular, to quantum communication within a communications network. Still more particularly, the present disclosure relates to an apparatus and method for allowing one communicator to establish multiple quantum encryption keys with different communicators in a communications network.
2. Background
Quantum communication involves encoding information in quantum bits. As used herein, a “quantum bit,” which may be also referred to a qubit, is a two-state quantum mechanical system. The quantum mechanical system may be realized using, for example, without limitation, the polarization of a single photon. The qubit may have two polarization states, vertical polarization and horizontal polarization. Quantum mechanics allows a qubit to be in one state, the other state, or a superposition of both states at any given point in time.
Quantum cryptography is the use of quantum mechanical effects to perform cryptographic tasks, such as, for example, encrypting and decrypting data. Quantum key distribution is a widely used quantum cryptographic technique that allows secure point-to-point communication. Point-to-point communication may be communication between a sender and a receiver over a communications channel between the sender and the receiver.
With quantum key distribution, the sender and the receiver may produce a shared random encryption key that is known only to them. The random encryption key may be a set of data bits that have been encoded using qubits. The sender encrypts the data using the random encryption key and sends this quantum encrypted data to the receiver. The receiver decrypts the quantum encrypted data using the random encryption key. This type of quantum encryption may ensure secure communications over standard communications channels, such as, for example, unsecure public communications channels.
However, with some currently available methods for communicating using quantum key distribution, network communications may be difficult. For example, in some cases, a communicator may be set up to send encrypted data or receive encrypted data, but not both. In other cases, a receiving communicator may only be configured for communications with a transmitting communicator and may be unable to communicate with a third communicator in the same communications network. Consequently, using quantum key distribution to exchange encrypted data over a large communications network may be more difficult than desired and, in some cases, may not be feasible. Therefore, it would be desirable to have a method and apparatus that address at least some of the issues discussed above, as well as other possible issues.